Echolocation. The bat can't use its blindsight while deafened.
Keen Hearing. The bat has advantage on Wisdom (Perception) checks that rely on hearing.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 9 (2d6 + 2) piercing damage and 2 (1d4) cold damage.
Piercing screech (recharge 6). Ranged Attack, Range: 20 ft diameter circle: Every creature, except Artic Swamp Bats or a deafened creature, in a 20 ft diameter circle with as center the bat queen must make a DC 14 Constitution Saving Throw, on a failure the creature takes 13 (2d8+4) physic damage and the creature becomes deafened for 1d4 rounds. On a succesfull saving throw the creature takes half damage and is not deafened.
Description
When an evil wizard and a white dragon changed a swamp into a frozen landscape, the local flora and fauna changed with it and so were the artic swamp bats created. But every group of artic swamp bats has a queen. The queen is a large bat with a pair of large wings that has a pattern on it that she can use to hide herself, also she has a snowwhite skin, piercing blue eyes, giant icicles as fangs and a blue arcane symbol on her forehead.
Lair and Lair Actions
While in her lair the bat queen has advantage on stealth checks and she regain her piercing screech on a 5 or a 6. Also she can, as an action, summon 3 Artic Swamp Bats in her lair once per short rest.